#include<bits/stdc++.h> using namespace std; int main(){ const int N=1e4+10; int n,m,a[N],s[N],ans,maxx; int q[N],t,rt[N]; int main(){ cin >> n; for(int i=1;i<=n;i++){ cin >> a[i]; s[i]=s[i-1]+a[i]; } for(int i=1;i<=n;i++){ while(t!=0 && a[q[t]]<=a[i]){ rt[q[t]]=i; q[t--]=0; } q[++t]=i; } for(int i=1;i<=n;i++){ if(rt[i]!=0){ ans+=(rt[i]-i-1)*min(a[rt[i]],a[i])-(s[rt[i]-1]-s[i]); i=rt[i]-1; } else{ break; } } cout << ans; return 0; }